The present invention relates to a conveyor belt support mechanism which is used to resiliently support a conveyor belt during loading and in particular to a conveyor belt support mechanism having a resistance to deformation by compression or flexure which resistance may be adjusted to meet particular operating conditions.
The belt of a conveyor is loaded with the material to be conveyed in an impact zone of a transfer point. The load material may be sand, gravel, coal, boulders, logs or other large or lumpy material masses. The vertical distance the load material falls as it is loaded onto the belt may vary from a few feet, such as when the material is loaded from the bucket of an end loader, to distances greater than thirty feet when the material is loaded through a conveyor chute. As the load material drops onto the belt the load material creates impact forces on the belt. The magnitude of the impact forces will vary depending upon the mass of the load material and the velocity of the load material when it impacts the belt. The impact forces applied to the belt during loading stretch the belt and create cracks, tears and other damage to the belt. The impact forces also result in excessive belt sag which breaks the seal between the edges of the belt and the lower edges of the conveyor skirtboards which contain the load material on the belt during loading. This allows an increase in the amount of load material which falls off of the belt over the side edges during loading. High impact forces in the load zone damage conventional impact rollers, shafts, and bearings.
Conveyor belt support mechanisms such as impact cradles have previously been used to support the belt of a conveyor in the impact zone of a transfer point. One such cradle is the GUARDABELT.RTM. impact cradle manufactured and sold by Martin Engineering of Neponset, Ill., the applicant herein. Such impact cradles typically include a plurality of metal beams including a T-shaped web and flange which extend longitudinally or transversely underneath the upper run of the belt in the impact zone of the transfer point. A bar or block of solid rubber having a T-shaped slot in its lower surface is slidably mounted on each beam with the T-shaped web and flange being located within the T-shaped slot. The upper surface of the rubber block may be coated with a low friction material such as ultra high molecular weight polyethylene to provide a low friction surface over which the belt slides.